Depends how you subscribed to the Fubo subscription. (either through Roku or directly with Fubo).
Try going to your online Roku account https://my.roku.com/account and look under "Manage your Subscriptions".
Otherwise, if you do not see your Fubo subscription there in the Roku subscriptions, try going to Fubo website https://www.fubo.tv/welcome and Sign in over there to your Fubo account.
Roku Community Streaming Expert
Just another Roku user... I am not a Roku employee.
Insignia RokuTV, Ultra 4660x, Premiere+ 3921, Express 4k+ 3941